Hey Option Paralysis! Thanks for writing this.
The original sound designer on this and I looked at this in-game and it does seem to match what was on the skins spotlights video. We're wondering if you were referencing this video of Skins Spotlight?:
https://www.youtube.com/watch?v=iBM1eKJe51E&t
There was a previous version of a Skins Spotlight video where it had base Olaf SFX playing before it was updated for SKT-unique sounds.
Our other thought is that Skins Spotlight records these videos in an isolated area of the map where no other champion sounds are playing (also slightly zoomed in which is why the lightning looks bigger), so everything sounds bigger and more impactful. The SKT unique sounds are leveled to be around the same volume as base Olaf.
Let me know if this isn't the issue you are referring to though! We're happy to look into it further if there's something we're missing on our end. Thanks!